Category: Marine Invertebrates

We were simply spellbound watching a reef squid feeding at night on our recent BVI Multi Sport Sailing Adventure! The video captures the pulsating chromatophore color cells and the lighter feeding tentacles waiting to strike. It happened so quickly that we missed capturing it on the video, but we’ will all remember the rapid strike and entanglement of a tiny fry fish, possibly a silverside.

The next morning, several of us encountered a school of over 60 reef squid watching us as we watched them! So many great moments in the Caribbean! Join us at www.bluewaterventures.org.

During our naturalist-led kayaking trips in Elkhorn Slough, we discuss what lives both above and below this rich ecological wetland area. The eelgrass beds are expanding due to an interplay among three Slough species.

A fascinating relationship has developed among the Taylor sea hare, their crab predator and the charismatic coastal marine mammal, the southern sea otter, Enhydra lutris nereis. During the early 1980’s, Elkhorn Slough and its associated eelgrass beds experienced a recruitment of the southern sea otter. As the otter’s range expanded into the slough, the population of Phyllaplisai taylori expanded correspondingly since otters started keeping a check on several crab species, which prey on the slug.

Not only did Phyllaplisai taylori expand in numbers but also they tended to live longer and grow larger with fewer pressures from crab predation.

As the slugs flourished in the Elkhorn Slough, the eelgrass beds became notably healthier. The slugs grazed upon many of the encrusting algae forms that would otherwise compete with eelgrass for sunlight. Acting as a nursery arena for a variety of marine fauna, healthy beds of Zostera marina is a highly desirable trend.

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During certain times of the year, we observe a high density of certain sea jellies such as the Red Eye Sea Jelly caught on video here.

Our Blue Water adventures are planned according to the tides, not a bad way to live at all! The recent extreme high and low tides, rain or shine have offered some true adventures along our California Coast.

Our week of King tides promoted by the alignment of the earth moon and sun offers so many opporunties to see our coast in a new perspective…get out there and look around or join us at http://www.bliewaterventures.org.

Always incredible discoveries in the shallows of Elkhorn Slough. The predatory sea slug, Navanax was noticed by one of our young clients on a private guided family outing today.
Using chemoreceptors, this colorful slug seeks out the slime trails produced by other slugs such as the colorful hermissenda nudibranch.

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Navanax is a voracious predator known to both eat and mate with other Navanax slugs it may encounter. Join us on a private family outing with http://www.bluewaterventures.org.

Our group of Mt Modonna Students were thrilled to learn about the California Sea Hare during our kayaking field trip to Elkhorn Slough. Sea hares, a large marine slug can emit a midly toxic purple dye as a defense. Slow moving grazers, they are simultaneous hermaphrodites and are sometimes found in large mating masses known as daisy chains or roman circles

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We also found the gelantious Ctenphore or comb jelly which empowers sicky cells rather than stinging cells like the true sea jellies (cnidarians) employ.

Mt Modonna’s Pal program matches a senior as a role model with a 3rd grader during adventures throughout the school year. Super cool and highly effective concept.

Teachers, join us on a naturalist-led field trip with bluewaterventures.org. We love our outdoor classroom!

Truly a great find yesterday while tidepooling at Davenport Landing, Octopus rubenscens, the red octopus! Watch closely and you will see that it’s spotted appearance mimics the bits of shell that are adhering to the sea anemones in the background. The spots disappear for a moment and the body develops a deep red hue as it passes over a patch of purple urchins then quickly develops the molted spots as it nears the shell laden anemones again. Incredible.
Octopus are masters of disguise and accomplish their pigment changes using chromatophores,1000’s of color cells that are embedded in their skin. By expanding or contracting these sacs of pigment they can instantaneously alter their color to match their surroundings. They may even morph the texture of their skin to mimic algae, rocks or coral.

Last night we had an amazing light show during our first of several bioluminescence night paddles in Elkhorn Slough. Before the water began to sparkle with light producing dinoflagellates, sea otters and harbor seals popped up near by. Marine mammal interactions are quite different at night. Many species produced a “cold light”, a chemical reaction that emits sparks of light. Bioluminescence may serve as a warning, a lure, communication or mate selection. As our paddles glided through the water, light exploded below us, light dripping from the paddles.

We’ve added 2 more Bioluminescence night paddles, Sept 12th and 13th. We hope teachers will bring their students as well booking a school field trip during September and early October. Details at:www.bluewaterventures.org. Photos from internet, my water camera is in repair!

Each year during our Caribbean programs in Belize and the British Virgin Islands, our group is invariably drawn to the Caribbean Reef Squid, Sepioteuthis sepioidea. Even seasoned snorkelers become overwhelmed by the explosion of colorful activity found on a coral reef. Suspended in blue water, an erie feeling that something is watching you creeps into your consciousness. A quick glance around reveals a squadron of reef squid. Swim away and they follow. Move towards them and they quickly change color, a deep red if near the reef or pale if over sand, masters of camouflage.

They may even create false eyes on their posterior end as seen here. The eyes will instantaneously vanish once the threat of a predator is gone. Quite incredible.

The picture below reveals an unusual white blotch across the dorsal side. I have watched reef squid for decades and have rarely seen such coloration. It appears as though we may have interrupted the amorous intentions of a courting male.

Reef squid not only expand and contract the chromatophore cells embedded in their skin to conceal themselves, but do so as part of their mating ritual. Males may flash an impressive zebra pattern to the female who is revealing a blotchy saddle indicating her sexual receptivity. Mate selection is a serious business to a female reef squid. She will die soon after depositing her fertilized eggs in a safe corner of the ocean floor. Like most cephalopods, the life of the Caribbean Reef Squid is relatively short. They are thought to live for one year, mate and die.

Join Blue Water Ventures on a naturalist-led adventure to the reefs, rain forest, kelp beds and beyond!